This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Background: The presence of retroviral infection in nonhuman primate research animals makes them unsuitable for a number of research studies. In addition, the presence of B-virus in nonhuman primates used in research is a significant occupational safety and health concern. The specific pathogen free (SPF) program was created to provide rhesus monkeys seronegative for SIV, SRV, STLV-1, and B-virus. Methods: Yearling rhesus are housed with peers from their natal groups while viral screening occurs during years 1-3 and are then moved into larger breeding groups. Animals testing positive for viral agents are removed from the SPF program. Yearling rhesus macaques are currently being removed from the conventional breeding colony for inclusion in the SPF program. Results/Discussion: The colony currently consists of 648 animals (217 Chinese-origin rhesus and 431 Indian-origin rhesus). In 2008, a total of 47 animals were assigned to core and affiliate researchers.